Characterization of edgeless pixel detectors coupled to Medipix2 readout chip

VTT has developed a straightforward and fast process to fabricate four-side buttable (edgeless) microstrip and pixel detectors on 6 in. (150 mm) wafers. The process relies on advanced ion implantation to activate the edges of the detector instead of using polysilicon. The article characterizes 150 μm thick n-on-n edgeless pixel detector prototypes with a dead layer at the edge below 1 μm. Electrical and radiation response characterization of 1.4×1.4 cm² n-on-n edgeless detectors has been done by coupling them to the Medipix2 readout chips. The distance of the detector's physical edge from the pixels was either 20 or 50 μm. The leakage current of flip-chip bonded edgeless Medipix2 detector assembles were measured to be ∼90 nA/cm² and no breakdown was observed below 110 V. Radiation response characterization includes X-ray tube and radiation source responses. The characterization results show that the detector's response at the pixels close to the physical edge of the detector depend dramatically on the pixel-to-edge distance.